containers provide a reasonable level of abstraction/isolation for applications, and have been used in production for some years now. Docker may be shiny, but containers not so much.
Also, shout out to the fanboys for downvoting my question, which was just a question asking for thoughts and answers and didn't make any statement whatsoever.
It has literally nothing to do with the ability to upgrade independent pieces on the sysadmin's schedule and everything to do with abstracting sysadmins clean out of the process. The entire profession has established itself as a roadblock to progress, so like good engineers do, we're busy coding the problem away.
Basically.